Many combinations of interface structures and associated gaskets are well known in the design of fluid delivery systems. These structures include flanges, glands, component connections, and other elements that enable mechanical assembly of various system elements forming an arrangement of interconnected fluid pathways.
Representative fluid delivery systems are found among industrial equipment producing fine chemicals, petroleum products, or semiconductors, for example, and may be subjected to vacuum or pressure or purity requirements and/or combinations thereof. Fluid pathways among elements intended for manipulating process materials within semiconductor manufacturing equipment usually require attention to maintaining high purity of the delivered reactants, and also typically have a much smaller cross-section than fluid pathways used in petrochemical plants, for example. In many cases, practitioners have found that metallic gaskets provide superior performance, particularly regarding diffusion of process fluid or contaminants through the gasket and consequent resistance to undesirable leakage, in preference over polymer materials.
One known type of fluid pathway joint uses a ring-shaped flat metallic gasket compressed between nominally identical shaped annular projections that surround circular conduit openings of opposing apparatus elements. The annular projections are urged axially toward one another, causing permanent plastic deformation of the ductile metallic gasket to create a seal that will resist leakage of even difficult-to-contain fluids such as helium. Representative examples of such joints may be seen, for example, in U.S. Pat. No. 3,208,758 issued to Carlson and Wheeler (familiarly known as the Varian® Conflat® flange), in U.S. Pat. No. 3,521,910 issued to Callahan and Wennerstrom (familiarly known as the Swagelok® VCR® fitting), and in U.S. Pat. No. 4,303,251, issued to Harra and Nystrom.
Another known type of fluid pathway joint uses a ring-shaped metallic gasket of complex shape compressed between nominally identical shaped annular projections that surround circular conduit openings of opposing apparatus elements. Representative examples of such joints are disclosed in U.S. Pat. No. 4,854,597 to Leigh, in U.S. Pat. No. 5,505,464 to McGarvey, and in U.S. Pat. No. 6,135,155 to Ohmi et al. (an early version of the W-seal joint type well known now in the industry). The '155 patent additionally provides a separate retainer for holding and centering the gasket during assembly of the joint. Such separate retainer structures may also be seen in U.S. Pat. No. 5,673,946 and U.S. Pat. No. 5,758,910, both issued to Barber and Aldridge, and in U.S. Pat. No. 7,140,647 to Ohmi et al.
Yet another known type of fluid pathway joint, familiarly known in the industry as the C-seal joint type, uses a ring-shaped metallic gasket of complex shape which is compressed between opposing apparatus elements, wherein the face of at least one element has a circular counterbore depression to receive the gasket. Representative examples of such joints are disclosed in, for example, U.S. Pat. No. 5,354,072 to Nicholson, U.S. Pat. No. 6,042,121, to Ma et al., U.S. Pat. No. 6,357,760 and U.S. Pat. No. 6,688,608, both issued to Doyle, and U.S. Pat. No. 6,409,180 issued to Spence and Felber. The '180 patent to Spence and Felber additionally discloses a separate retainer for holding and centering the gasket during joint assembly. Such separate retainer structures may also be seen in U.S. Pat. No. 5,730,448 to Swensen et al., U.S. Pat. No. 5,984,318 to Kojima and Aoyama, U.S. Pat. No. 6,845,984 to Doyle, and U.S. Pat. No. 6,945,539 to Whitlow et al.
Still another known type of fluid pathway joint, known in the industry as the Z-Seal type, uses a ring-shaped flat metallic gasket compressed between opposing apparatus elements wherein mating features surrounding circular conduit openings create corners that shear into the gasket. This type of corner-shear joint is illustrated in U.S. Pat. No. 5,803,507 and U.S. Pat. No. 6,394,138, both issued to the present inventor, Kim Ngoc Vu, and it also utilizes a retainer structure. All of the foregoing patents are herein expressly incorporated by reference, in their entirety.
In the majority of the preceding design examples, there is considerable risk of adversely scratching a face of the gasket prior to joint assembly and such damage thereby making a joint free of leaks unachievable. Gasket centering by a separate retainer provides a desirable consistency of alignment between the fluid pathway conduit ports and the central passageway through the gasket, but incurs undesirable added expense. Within some fluid delivery systems used for semiconductor manufacturing processes, there are situations using multiple types of pathway joints simultaneously, and that situation requires equipment maintenance personnel to stock and have available an undesirably large inventory of various kinds of spare gaskets.